title: Transcriptional response of Mexican axolotls to Ambystoma tigrinum virus (ATV) infection.
abstract: BACKGROUND
  Very little is known about the immunological responses of amphibians to pathogens that are causing global population declines. We used a custom microarray gene chip to characterize gene expression responses of axolotls (Ambystoma mexicanum) to an emerging viral pathogen, Ambystoma tigrinum virus (ATV).
  
  
  RESULTS
  At 0, 24, 72, and 144 hours post-infection, spleen and lung samples were removed for estimation of host mRNA abundance and viral load. A total of 158 up-regulated and 105 down-regulated genes were identified across all time points using statistical and fold level criteria. The presumptive functions of these genes suggest a robust innate immune and antiviral gene expression response is initiated by A. mexicanum as early as 24 hours after ATV infection. At 24 hours, we observed transcript abundance changes for genes that are associated with phagocytosis and cytokine signaling, complement, and other general immune and defense responses. By 144 hours, we observed gene expression changes indicating host-mediated cell death, inflammation, and cytotoxicity.
  
  
  CONCLUSIONS
  Although A. mexicanum appears to mount a robust innate immune response, we did not observe gene expression changes indicative of lymphocyte proliferation in the spleen, which is associated with clearance of Frog 3 iridovirus in adult Xenopus. We speculate that ATV may be especially lethal to A. mexicanum and related tiger salamanders because they lack proliferative lymphocyte responses that are needed to clear highly virulent iridoviruses. Genes identified from this study provide important new resources to investigate ATV disease pathology and host-pathogen dynamics in natural populations.
authors.affiliation: School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA. jdstewart@wsu.edu
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Cotter
authors.forename: Andrew
authors.initials: A
authors.lastname: Storfer
authors.forename: Robert B
authors.initials: RB
authors.lastname: Page
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Beachy
authors.forename: S Randal
authors.initials: SR
authors.lastname: Voss
mesh_terms: D000558:Ambystoma mexicanum / Q000235:genetics* / Q000276:immunology / Q000821:virology*; D000818:Animals; D004266:DNA Virus Infections / Q000276:immunology / Q000662:veterinary*; D005786:Gene Expression Regulation; D054884:Host-Pathogen Interactions; D008214:Lymphocytes / Q000276:immunology; D017995:Ranavirus / Q000276:immunology*; D014158:Transcription, Genetic